The present invention relates to a silver halide photographic light-sensitive material, and to a method of forming a high-contrast negative image by using the light-sensitive material. Specifically, the present invention relates to an ultrahigh-contrast negative-type photographic light-sensitive material suitable for a silver halide light-sensitive material used in a photomechanical process, and to a method of forming an image by using the light-sensitive material.
In a photomechanical process in the field of graphic arts, a method is adopted in which a photographic image having a continuous gradation is converted into a so-called dot image, for expressing the shade of an image by a difference in the size of a dot area, and the dot image is combined with an image obtained by taking photographs of letterings and line originals, to thereby produce a printing master plate. It has been required for a silver halide light-sensitive material used in such an application to have ultrahigh-contrast photographic characteristics, such that an image portion is clearly separated from a non-image ortion, to improve the reproducibility of letterings, line originals, and dot images.
As a system meeting the demand for the ultrahigh-contrast photographic characteristics, the so-called lithographic developing system has been known, in which a silver halide light-sensitive material containing silver chlorobromide is processed in a hydroquinone developer, in which the effective concentration of a sulfite ion is made extremely low, to form a high-contrast image. However, since the concentration of a sulfite ion in the developer is low in this system, the developer is extremely unstable against air oxidation, requiring a large amount of a replenishing developer to maintain stable activity of the solution.
Image formation systems capable of obtaining ultrahigh-contrast photographic properties through development with a processing solution having good storage stability, solving the instability problem concerning the image formation in the lithographic developing system, are disclosed, for example, in U.S. Patents Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,269,922, 4,272,606, 4,311,781, 4,332,878, 4,618,574, 4,634,661, 4,681,836, 5,650,746, and the like. These patents disclose the system in which a surface-latent-image-type silver halide photographic light-sensitive material, to which a hydrazine derivative is added, is processed using a developer containing, as a developing agent, hydroquinone/metol or hydroquinone/phenidone containing 0.15 mol/l or more of a sulfurous acid preservative, and having a pH of 11.0 to 12.3, to form an ultrahigh-contrast negative image having a xcex3 value exceeding 10. According to this system, ultrahigh-contrast and highly-sensitive photographic characteristics are obtained. Also, a high-density sulfite can be added in the developer, and therefore the stability of the developer against air oxidation is improved more outstandingly than that of a conventional lithographic developer.
In order to complete a high-contrast image formation using hydrazine derivatives, it is necessary to process with a developing solution having a pH of 11 or more, usually 11.5 or more. Even though the use of a high-density sulfurous acid preservative makes it possible to heighten the stability of a developer, it is necessary to use such a developer having a high pH value as aforementioned, to obtain an ultrahigh-contrast photographic image. Therefore, even if the preservative is present, the developer is easily oxidized and hence unstable. To solve this problem, attempts have been made to attain an ultrahigh-contrast image at lower pHs, to improve the stability further.
For example, U.S. Pat. No. 4,269,929 (JP-A-61-267759 (the term xe2x80x9cJP-A-xe2x80x9d as used herein means an unexamined published Japanese patent application)), U.S. Pat. No. 4,737,452 (JP-A-60-179734), U.S. Pat. Nos. 5,104,769 and 4,798,780, JP-A-1-179939, JP-A-1-179940, U.S. Pat. Nos. 4,998,604 and 4,994,365, and JP-A-8-272023 disclose methods using a highly active hydrazine derivative and a nucleation accelerator, to obtain an ultrahigh-contrast image, by using a developer having a pH of less than 11.0.
Silver halide photographic light-sensitive materials used in such an image-formation system self-contains a highly active compound, posing problems concerning storage stability, such as variation in sensitivity and increased fogging during storing. Therefore, a need has existed for silver halide photographic light-sensitive materials that are improved in terms of these drawbacks.
The present invention is a silver halide photographic light-sensitive material that has at least one silver halide emulsion layer on a support, the light-sensitive material containing a surfactant represented by the following formula (F), and having the characteristic curve that a gamma in the range of an optical density from 0.3 to 3.0 is 5.0 or more, on the characteristic curve shown in a rectangular coordinate where a logarithmic exposure amount (the x axis) and an optical density (the y axis) are indicated according to the same unit length;
[Rfxe2x88x92(Rc)n]mxe2x88x92Zxe2x80x83xe2x80x83formula (F)
wherein Rf represents a perfluoroalkyl group, Rc represents an alkylene group, Z represents a group having an anionic group, cationic group, amphoteric ionic group, or nonionic polar group, n is an integer of 0 or 1, and m is an integer of 1 to 3.
Other and further features and advantages of the invention will appear more fully from the following description, taken in connection with the accompanying drawing.